Prostate cancer is one of the most common forms of cancer found in Western men and the second leading cause of cancer death in Western men. When prostate cancer is confined locally, the disease can usually be treated by surgery and/or radiation. Advanced disease is frequently treated with anti-androgen therapy, also known as androgen deprivation therapy. Administration of anti-androgens blocks androgen receptor (AR) function by competing for androgen binding; and therefore, anti-androgen therapy reduces AR activity. Frequently, such therapy fails after a time, and the cancer becomes hormone refractory, that is, the prostate cancer no longer responds to hormone therapy and the cancer does not require androgens to progress.
Overexpression of AR has been identified as a cause of hormone refractory prostate cancer (Nat. Med., 10:33-39, 2004; incorporated herein by reference). Overexpression of AR is sufficient to cause progression from hormone sensitive to hormone refractory prostate cancer, suggesting that better AR antagonists than the current drugs may be able to slow the progression of prostate cancer. It has been demonstrated that overexpression of AR converts anti-androgens from antagonists to agonists in hormone refractory prostate cancer. This work explains why anti-androgen therapy fails to prevent the progression of prostate cancer.
The identification of compounds that have a high potency to antagonize AR activity would overcome the hormone refractory prostate cancer and slowdown the progression of hormone sensitive prostate cancer. Such compounds have been identified by Sayers et al. (WO 2007/126765, published Nov. 8, 2007; which is incorporated herein by reference). One compound is known as A52, a biarylthiohydantoin, and has the chemical structure:
Another compound A51 has the chemical structure:
Both of these compounds share the same western and central portions. Given the need for larger quantities of pure A51 and A52 for pre-clinical and clinical studies, there remains a need for a more efficient synthesis of the compound from commercially available starting materials.